U.S. patent number 8,956,710 [Application Number 13/502,863] was granted by the patent office on 2015-02-17 for vacuum insulation panel.
This patent grant is currently assigned to LG Hausys, Ltd.. The grantee listed for this patent is Jung Pil Han, Sung Seock Hwang, Suk Jang, Seung Min Jeon, Myung Lee. Invention is credited to Jung Pil Han, Sung Seock Hwang, Suk Jang, Seung Min Jeon, Myung Lee.
United States Patent |
8,956,710 |
Jang , et al. |
February 17, 2015 |
Vacuum insulation panel
Abstract
Disclosed are a vacuum insulation panel, a method for
manufacturing the same and an insulation box having the same. By
cutting the core material correspondingly to shape and thickness of
the absorbent without cut of the core material and pressing the
absorbent securing part to form the groove for placing the
absorbent therein, the vacuum insulation panel prevents partial
deterioration of heat transmission caused by the cutoff of the core
material or deterioration of the smoothness caused by placing the
absorbent above the core material or between the core materials.
Particularly, it is possible to prevent the phenomenon that the
periphery is pressed together, which is shown in a conventional
press process, to thereby improve the smoothness by cutting the
core material in shape and depth corresponding to the shape and
thickness of the absorbent prior to the press of the absorbent
securing part. Therefore, it is possible to provide an energy
saving insulation box by reducing generation of wrinkle or poor
sealing of the surface material of the vacuum insulation panel to
thereby increase insulation efficiency of the vacuum insulation
panel for a long time.
Inventors: |
Jang; Suk (Seoul,
KR), Hwang; Sung Seock (Chungcheongbuk-do,
KR), Jeon; Seung Min (Busan, KR), Lee;
Myung (Gyeonggi-do, KR), Han; Jung Pil (Ulsan,
KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
Jang; Suk
Hwang; Sung Seock
Jeon; Seung Min
Lee; Myung
Han; Jung Pil |
Seoul
Chungcheongbuk-do
Busan
Gyeonggi-do
Ulsan |
N/A
N/A
N/A
N/A
N/A |
KR
KR
KR
KR
KR |
|
|
Assignee: |
LG Hausys, Ltd. (Seoul,
KR)
|
Family
ID: |
43900774 |
Appl.
No.: |
13/502,863 |
Filed: |
October 5, 2010 |
PCT
Filed: |
October 05, 2010 |
PCT No.: |
PCT/KR2010/006783 |
371(c)(1),(2),(4) Date: |
April 19, 2012 |
PCT
Pub. No.: |
WO2011/049304 |
PCT
Pub. Date: |
April 28, 2011 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20120207963 A1 |
Aug 16, 2012 |
|
Foreign Application Priority Data
|
|
|
|
|
Oct 23, 2009 [KR] |
|
|
10-2009-0101427 |
|
Current U.S.
Class: |
428/69 |
Current CPC
Class: |
F16L
59/065 (20130101); E04B 1/803 (20130101); Y02A
30/242 (20180101); Y02B 80/10 (20130101); F25D
2201/14 (20130101); Y02B 80/12 (20130101); Y10T
29/49826 (20150115); Y10T 428/231 (20150115) |
Current International
Class: |
F16L
59/065 (20060101) |
Field of
Search: |
;428/69 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
1724513 |
|
Nov 2006 |
|
EP |
|
10-122477 |
|
Jan 1998 |
|
JP |
|
11-281245 |
|
Oct 1999 |
|
JP |
|
2004-011709 |
|
Jan 2004 |
|
JP |
|
2004-218747 |
|
Aug 2004 |
|
JP |
|
2006-021429 |
|
Jan 2006 |
|
JP |
|
2006-021429 |
|
Jan 2006 |
|
JP |
|
Primary Examiner: Thomas; Alexander
Attorney, Agent or Firm: McKenna Long & Aldridge,
LLP
Claims
The invention claimed is:
1. A vacuum insulation panel, comprising: a core material; a
surface material for covering the core material; and an absorbent
placed in a securing part of the core material, wherein the
securing part of the core material is a groove formed by cutting
the core material in shape and depth corresponding to shape and
thickness of the absorbent and pressing the cut portion, wherein
the surface material is a multilayer film which includes a thermal
bonding layer, a gas barrier layer, a first protective layer and a
second protective layer, and wherein the first protective layer is
a polyamide layer and the second protective layer is a polyethylene
terephthalate film (K-PET) of which outside is coated with
polyvinylidene chloride (PVDC).
2. The vacuum insulation panel as set forth in claim 1, wherein the
core material is a glass fiber board, a glass wool or a stacked
body of one or more selected therefrom.
3. The vacuum insulation panel as set forth in claim 2, wherein the
stacked body is a stacked body of glass wool.
4. The vacuum insulation panel as set forth in claim 1, wherein the
core material is decompressively sealed between the surface
materials.
5. The vacuum insulation panel as set forth in claim 1, wherein the
thermal bonding layer is made of one or more resin selected from
the group consisting of linear low density polyethylene (LLDPE),
low density polyethylene (LDPE), very low density polyethylene
(VLDPE) and high density polyethylene (HDPE).
6. The vacuum insulation panel as set forth in claim 1, wherein the
thermal bonding layer is made of LLDPE.
7. The vacuum insulation panel as set forth in claim 1, wherein the
gas barrier layer is a metal foil layer or a plastic film deposited
with metal.
8. The vacuum insulation panel as set forth in claim 7, wherein the
metal used in the metal foil layer or the plastic film deposited
with metal is aluminum.
9. The vacuum insulation panel as set forth in claim 7, wherein the
plastic film deposited with metal is made of one or more resin
selected from the group consisting of polyamide, polyimide,
polypropylene, polyethylene terephthalate, polyethylene
naphthalate, polyacrylonitrile, polyvinyl alcohol and ethylene
vinyl alcohol.
10. The vacuum insulation panel as set forth in claim 1, wherein
the gas barrier layer includes an aluminum foil and an ethylene
vinyl alcohol film.
11. The vacuum insulation panel as set forth in claim 1, wherein
the absorbent is calcium oxide.
12. The vacuum insulation panel as set forth in claim 1, wherein
the absorbent is packaged in a packaging material.
13. The vacuum insulation panel as set forth in claim 12, wherein
the packaging material includes one or more layer selected from the
group consisting of water resisting paper layer, air permeable
polyethylene layer, air permeable polypropylene layer and air
permeable polyethylene propylene layer.
14. The vacuum insulation panel as set forth in claim 12, wherein
the packaging material is a stacked film including water resisting
paper layer and air permeable polypropylene layer.
15. A method of manufacturing a vacuum insulation panel, which
includes: a core material; a surface material for covering the core
material; and an absorbent placed in a securing part of the core
material, wherein the securing part of the core material is formed
by cutting the core material in shape and depth corresponding to
shape and thickness of the absorbent and pressing the cut portion,
wherein the surface material is a multilayer film which includes a
thermal bonding layer, a gas barrier layer, a first protective
layer and a second protective layer, and wherein the first
protective layer is a polyamide layer and the second protective
layer is a polyethylene terephthalate film (K-PET) of which outside
is coated with polyvinylidene chloride (PVDC).
Description
This application is a National Stage Entry of International
Application No. PCT/KR2010/006783, filed Oct. 5, 2010, and claims
the benefit of Korean Application No. 10-2009-0101427, filed on
Oct. 23, 2009, which is hereby incorporated by reference for all
purposes as if fully set forth herein.
TECHNICAL FIELD
The present invention relates to a vacuum insulation panel, a
method for manufacturing the same and an insulation box having the
same.
BACKGROUND ART
A refrigerator is a product designed to keep an internal
temperature thereof at a predetermined temperature or lower for the
purpose of fresh storage of food. Therefore, in order to keep cold
air generated in an inside of the refrigerator and prevent heat
outside the refrigerator from permeating into the inside of the
refrigerator, an insulation layer is formed between an inner case
and an outer case of the refrigerator during manufacture of the
refrigerator. The insulation layer is generally formed by filling
foaming liquid between the inner case and the outer case and
hardening the foaming liquid. An inside of a microcell of a
polyurethane insulation layer is filled with carbon dioxide gas and
foaming agent gas generated by vaporization due to high heat during
reaction. However, CFC, HCFC and cyclopentane, or the foaming agent
gas, and the carbon dioxide has high thermal conductivity, which
causes deterioration in insulation property of the polyurethane
insulation layer. Therefore, a vacuum insulation panel having high
insulation property is used to supplement the insulation effect of
the aforementioned polyurethane insulation layer. In general, a
vacuum insulation panel having a predetermined size is inserted
between the inner case and the outer case of the refrigerator and
conventional polyurethane foam is filled around the vacuum
insulation panel.
The vacuum insulation panel is an insulation panel, in which foamed
resin or fiber material is put as a core material into a surface
material, and has a considerably reduced thermal conductivity of a
gas by keeping an inside of the insulation panel in vacuum. In
order to keep the insulation performance of the vacuum insulation
panel for a long period, it is necessary to continuously keep the
inside of the insulation panel in vacuum. However, when a pinhole
is generated in the surface material during manufacture of the
vacuum insulation panel or sealing of a thermal bonding layer is
loosened with time, gas or moisture permeates into the inside of
the vacuum insulation layer to lower a degree of vacuum. Therefore,
to prevent the deterioration of the insulation performance,
inclusion of an absorbent such as silica gel, calcium oxide and
zeolite has been suggested.
This absorbent is generally placed above the core material or
between the core materials, or placed in a securing part made by
cutting some portion of the core material, and in this case, there
has been a problem that smoothness or the insulation performance is
deteriorated.
DISCLOSURE OF INVENTION
Technical Problem
It is an object of the present invention to provide a vacuum
insulation panel, in which an absorbent is placed such that
smoothness of the vacuum insulation panel can be improved and
deterioration of a thermal conductivity can be prevented.
Solution to Problem
As described above, when the absorbent is placed above the core
material or between the core materials, the smoothness of a vacuum
insulation panel is lowered and this may be a cause of generation
of a pinhole in a surface material or poor sealing of the surface
material to thereby deteriorate vacuum performance of the vacuum
insulation panel. Also, when an absorbent securing part is provided
by cutting some portion of the core material, a density of the core
material is reduced at the portion corresponding to the absorbent
securing part to thereby cause partial deterioration of the thermal
conductivity.
To solve the problem, the present invention provides a vacuum
insulation panel, in which an absorbent securing part of a core
material is formed by cutting the core material in shape and depth
corresponding to the shape and thickness of an absorbent and
pressing the cut portion.
In one embodiment, the present invention provides a vacuum
insulation panel including: a core material; a surface material for
covering the core material; and an absorbent placed in a securing
part of the core material, wherein the securing part of the core
material is a groove formed by cutting the core material in shape
and depth corresponding to the shape and thickness of an absorbent
and pressing the cut portion.
Also, the present invention provides a method of manufacturing a
vacuum insulation panel including: a core material; a surface
material for covering the core material; and an absorbent placed in
a securing part of the core material, wherein the securing part of
the core material is formed by cutting the core material in shape
and depth corresponding to the shape and thickness of an absorbent
and pressing the cut portion.
Preferably, the absorbent securing part is formed in a shape of a
groove by the press process. Preferably, the absorbent securing
part has a shape of a groove which has shape and depth
corresponding to shape and thickness of the absorbent. Preferably,
the absorbent securing part is previously cut in shape and depth
corresponding to the shape and thickness of the absorbent prior to
the press of the core material. In the present invention, the shape
and depth "corresponding to" the shape and thickness of the
absorbent do not means that the shape and depth are identical to
the shape and thickness of the absorbent, but means that the
securing part has such shape and depth that the groove can secure
the absorbent. Since the absorbent securing part is subjected to a
decompression process after cut and pressed, size and depth of the
absorbent securing part may differ before and after the
decompression. Therefore, the core material should be cut in
consideration of variation in the size and depth of the shape due
to the overall volume reduction. In the present description, when
the thickness of the absorbent and the depth of the absorbent
securing part are described identical, the depth of the absorbent
securing part may be a depth after decompression.
In a general press process in which press is performed without
cutting, periphery is pressed together with the portion to be
pressed and an overall shape of the core material may be twisted
according to strength of the core material to lower the smoothness.
The lowering in the smoothness results in long-term deterioration
of the insulation performance since the lowering in the smoothness
is a cause of generation of a pinhole in a surface material or poor
sealing of the surface material.
On the contrary, in the vacuum insulation panel of the present
invention, it is possible to prevent the phenomenon that the
periphery is pressed together, which has been shown in a
conventional press process, to thereby improve the smoothness by
cutting the core material in shape and depth corresponding to the
shape and thickness of the absorbent prior to the press of the
absorbent securing part. Therefore, use of the vacuum insulation
panel of the present invention can reduce generation of wrinkle or
poor sealing of the surface material of the vacuum insulation
panel. Moreover, since the absorbent securing part is not formed
into a groove shape by cutting off some portion of the core
material as described above, it is possible to prevent partial
deterioration in thermal conductivity due to difference in density
or thickness of the core material. Therefore, the vacuum insulation
panel can provide an energy saving insulation box since it can keep
the insulation effect for a long time.
Any material can be used for the core material, provided that it is
known to be usable in a vacuum insulation panel. The core material
may include, though not particularly limited to, one of inorganic
fiber such as glass fiber, organic fiber such as polyester fiber,
resin foam such as polyurethane, polyethylene and polypropylene,
inorganic powder such as silica, pearlite and carbon black, and
organic powder such as synthetic resin powder, or a combination
thereof. Also, a textile binder, or an inorganic or organic liquid
binder may be used to manufacture the core material. For example,
the core material may be manufactured by cutting fiber material
such as a stacked body of glass fibers and a stacked body of
organic fibers into suitable size and shape.
In one embodiment, the core material may be a glass fiber board, a
glass wool or a stacked body of one or more selected therefrom. For
example, the glass fiber board may be manufactured by dispersing
glass finer into an inorganic binder. Such glass fiber board may be
used in a single layer or in a form of a stacked body of 1 to 5
glass fiber boards. A thickness of the glass fiber board may be 1
to 16 mm when it is used in a single layer, and a thickness of one
sheet of the glass fiber board may be 4 to 10 mm when it is used in
a form of a stacked body. When the core material includes such
glass fiber board, aging of the core material may be performed
before the core material is received in the surface material to
remove moisture or gas present in the core material. It is
preferable that a heating temperature is 110.degree. C. or higher
in order to remove the moisture on the surface of the core
material, and particularly for the glass fiber, it is more
preferable that the aging is performed at 180.degree. C. or higher
in order to reduce a moisture content of the core material
maximally. For another example, a stacked body of glass wool made
by pressurizing and heating 1 to 4 glass wools for 5 to 15 minutes
at 500 to 500.degree. C. and stacking them may be used as the core
material. Alternatively, a core material having a composite
structure manufactured using the glass fiber board and
thermocompressed glass wool together may be used.
A diameter of the glass fiber used in the manufacture of the core
material is not particularly limited, but is preferably 1 to 10
.mu.m in consideration that a mean diameter of the glass fiber has
influence on thermal conductive property and cost of the glass
fiber.
Meanwhile, the absorbent securing part formed in the core material
is formed into a depth corresponding to a thickness of an
absorbent, and the core material has a thickness greater than the
depth of the absorbent securing part. Though not particularly
limited to, for example, the thickness of the core material is 5 to
20 mm, the thickness of the absorbent is 2 to 4 mm and the depth of
the absorbent securing part is 2 to 4 mm. When the absorbent
securing part is formed in accordance with the present invention,
difference in thickness between the portion where the absorbent is
present and the portion where the absorbent is not present is
reduced to 1 mm or less to thereby improve the smoothness.
In the vacuum insulation panel of the present invention, the core
material is decompressively sealed between the surface materials.
The surface material is a multilayer film which includes a thermal
bonding layer, metal foil layer and one or more protective layer.
The thermal bonding layer is present in the innermost layer of the
surface material to thermally bond the innermost layers of the one
or more multilayer film. Decompressive sealing by the surface
material is performed by placing the innermost layers of the one or
more multilayer film used as the surface material so as to face
with each other, and then bonding the thermal bonding layers, i.e.
the innermost layers with the core material being put therebetween
and at the same time discharging air from an inside of the surface
material to make the inside in vacuum state.
In order to enhance the sealing quality while increasing the
smoothness without generation of wrinkle or poor sealing when the
core material is decompressively sealed with the surface material,
the thickness of the surface material is preferably 60 to 130
.mu.m. Also, it is preferable that the surface material has
flexibility, which allows extension or bending within a range in
that it does not damage the gas barrier property according to the
shape or size of the core material during the manufacture of the
vacuum insulation panel.
In the vacuum insulation layer of the present invention, the
thermal bonding layer may be made of polyethylene resin such as
linear low density polyethylene (LLDPE), low density polyethylene
(LDPE), very low density polyethylene (VLDPE) and high density
polyethylene (HDPE), thermally bondable resin other than the
polyethylene or a mixture thereof. Since the polyethylene resin can
be boded at a relatively low temperature, it can be easily bonded
by additional heating and allows manufacture of the vacuum
insulation panel at a low cost. In one embodiment, the thermal
bonding layer is made of LLDPE. LLDPE has excellent mechanical
properties such as thermal bonding strength, pinhole resistance and
impact resistance as compared with HDPE or other thermally bondable
films. Also, employment of LLDPE in the thermal bonding layer of a
vacuum insulation panel enhances the gas barrier property since
LLDPE shows the gas barrier property equal to or higher than that
of HDPE.
The thermal bonding layer not only has a large influence on control
of gas permeation but also has a large influence on maintaining of
long-term insulation performance of a vacuum insulation panel.
Therefore, the thickness of the thermal bonding layer is, though
not particularly limited to, 30 to 70 .mu.m in consideration of
long-term stability of thermal bonding and mechanical strength of
the surface of the surface material when using a metal foil as the
gas barrier layer.
In the present invention, the gas barrier layer included in the
surface material can employ any material provided that it can be
used for the purpose of reduction of gas permeation. Though not
particularly limited to, a metal foil or a plastic film deposited
with metal, metal oxide or diamond-like carbon may be used as the
gas barrier layer. For example, the metal foil is an aluminum foil
or a stainless steel foil. Also, the material deposited on the
plastic film may include aluminum, iron, cobalt, nickel, zinc,
copper, silver, silica and alumina, but not particularly limited
thereto. Further, the material of the plastic film on which the
metal, etc. is deposited includes, though not particularly limited
to, one or more resin selected from the group consisting of
polyamide, polyimide, polypropylene, polyethylene terephthalate,
polyethylene naphthalate, polyacrylonitrile, polyvinyl alcohol and
ethylene vinyl alcohol. In one embodiment, the gas barrier layer
may be a metal foil, for example, an aluminum foil. In another
embodiment, the gas barrier layer may include an aluminum foil and
an ethylene vinyl alcohol film. When the ethylene vinyl alcohol
film is placed between the thermal bonding layer and the aluminum
foil, barrier performance of a bending portion is enhanced to
lengthen a long-term endurance life of an entire vacuum insulation
panel. Meanwhile, in order to ensure a sufficient gas barrier
property, a thickness of the gas barrier layer may be 4 to 10
.mu.m.
The surface material also includes one or more protective layer for
ensuring pinhole resistance and mechanical strength of the film.
The one or more protective layer may be made of one or more resin
selected from the group consisting of polyamide, polypropylene,
polyethylene terephthalate, polyacrylonitrile, polyvinyl alcohol
and ethylene vinyl alcohol, respectively. As the protective layer
that covers the innermost layer and the gas barrier layer is
provided, the vacuum insulation panel comes to have scratch
resistance and piercing resistance to thereby be able to prevent
generation of pinhole and give long-term reliability to the vacuum
insulation panel. In one embodiment, the surface material may
include, from the inner side thereof, a thermal bonding layer, a
gas barrier layer, a first protective layer and a second protective
layer. In one embodiment, the first protective layer may be a
polyamide layer and the second protective layer may be a
polyethylene terephthalate layer. Polyethylene terephthalate not
only has excellent surface protective effect but also is
inexpensive to thereby allow manufacture of a vacuum insulation
panel of the present invention with low cost. The polyethylene
terephthalate layer may, if necessary, employ a polyethylene
terephthalate film (K-PET) of which outside is coated with
polyvinylidene chloride (PVDC). The protective layer may have a
thickness of 30 to 50 .mu.m in consideration of pinhole resistance
or mechanical strength, and the thicknesses of the first protective
layer and the second protective layer can be properly controlled in
the aforementioned range according to physical properties of the
protective layer to be obtained.
Meanwhile, the vacuum insulation panel of the present invention
includes an absorbent that can absorb moisture or gas. Any material
can be used as the absorbent provided that it is known as a gas
absorbent or a moisture absorbent. For example, the absorbent may
be used in substitution or in combination with known absorbent
including a gas absorbent such as calcium oxide, quicklime and
metal oxide, alloy such as barium-lithium alloy, and hydrophobic
molecular sieve in which absorbing ability of volatile or
hydrophobic organic gas is increased. In one embodiment, the
absorbent is calcium oxide.
The absorbent may be one packaged in a packaging material. In the
present invention, the absorbent may be interpreted as a state of
being packaged in a packaging material. The packaging material for
the absorbent may employ an air permeable packaging material. For
example, the absorbent packaging material of the present invention
may include, though not particularly limited to, one or more layer
selected from the group consisting of water resisting paper layer,
air permeable polyethylene layer, air permeable polypropylene layer
and air permeable polyethylene propylene layer. For example, the
absorbent packaging material may be a stacked film including water
resisting paper layer and air permeable polyethylene layer, a
stacked film including water resisting paper layer and air
permeable polypropylene layer, or a stacked film including air
permeable polyethylene layer and air permeable polypropylene layer.
The air permeable resin layer includes a film layer or non-woven
layer having micropores. In one embodiment, the absorbent packaging
material may be a stacked film including water resisting paper
layer and air permeable polypropylene layer.
The present invention also provides an insulation box including the
above described vacuum insulation panel. The insulation box
includes an inner box, an outer box and a vacuum insulation panel
placed in a space formed by the inner box and the outer box. In the
space between the inner box and the outer box where the vacuum
insulation panel is placed, a foamed insulation material can be
provided. When the foamed insulation material is provided, at least
some of the vacuum insulation panel can be buried in the foamed
insulation material. In accordance with the present invention, it
is possible to provide an energy saving insulation box by reducing
generation of wrinkle or poor sealing of the surface material of
the vacuum insulation panel to thereby increase insulation
efficiency of the vacuum insulation panel for a long time.
By cutting the core material correspondingly to shape and thickness
of the absorbent without cut of the core material and pressing the
absorbent securing part to form the groove for placing the
absorbent therein, the vacuum insulation panel of the present
invention prevents partial deterioration of heat transmission
caused by the cutoff of the core material or deterioration of the
smoothness caused by placing the absorbent above the core material
or between the core materials. Particularly, it is possible to
prevent the phenomenon that the periphery is pressed together,
which is shown in a conventional press process, to thereby improve
the smoothness by cutting the core material in shape and depth
corresponding to the shape and thickness of the absorbent prior to
the press of the absorbent securing part. Therefore, in accordance
with the present invention, it is possible to provide an energy
saving insulation box by reducing generation of wrinkle or poor
sealing of the surface material of the vacuum insulation panel to
thereby increase insulation efficiency of the vacuum insulation
panel for a long time.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a sectional view illustrating a vacuum insulation panel
in accordance with an embodiment of the present invention.
FIG. 2 is a sectional view illustrating a surface material, in
which a side (A in FIG. 1) of the vacuum insulation panel in
accordance with an embodiment of the present invention is
enlarged.
FIG. 3 is a view illustrating a process of cutting a portion of the
securing part in the core material with a device for forming the
absorbent securing part in the core material and at the same time
pressing the portion of the securing part to form a groove.
FIG. 4 is a view illustrating a core material formed with an
absorbent securing part and an absorbent provided in the securing
part in accordance with an embodiment of the present invention.
BRIEF DESCRIPTION OF MAIN ELEMENTS
100: vacuum insulation panel 10: core material 12: absorbent
securing part 20: surface material 22: thermal bonding layer 24:
gas barrier layer 26: first protective layer 28: second protective
layer 30: absorbent 40: absorbent securing part forming device 42:
cutting knife 44: compression jig 46: compression spring 48: guide
jig
MODE FOR THE INVENTION
Practical and presently preferred embodiments of the present
invention are illustrative as shown in the following Examples.
However, it will be appreciated that those skilled in the art, on
consideration of this disclosure, may make modifications and
improvements within the spirit and scope of the present
invention.
EMBODIMENT
Hereinafter, an embodiment of the present invention will be
described in detail with reference to accompanying drawings. The
advantages, features and aspects of the invention will become
apparent from the following description of the embodiment with
reference to the accompanying drawings, which is set forth
hereinafter. It should be noted that the drawings are not to
precise scale and may be exaggerated in thickness of lines or size
of components for the purpose of convenience and clarity only.
FIG. 1 is a sectional view illustrating a vacuum insulation panel
100 in accordance with an embodiment of the present invention. The
vacuum insulation panel 100 includes a core material 10, an
absorbent 30 provided in an absorbent securing part 12 formed in
the core material 10, and a surface material 20 that covers the
core material 10 and the absorbent 30. The core material 10 is
surrounded and thus decompressively sealed by two surface materials
20.
FIG. 2 is a view illustrating the core material 10 formed with the
absorbent securing part 12 and the absorbent 30 provided in the
absorbent securing part 12 in accordance with an embodiment of the
present invention. The absorbent securing part 12 is formed on the
core material 10 in a shape of a groove having depth and shape
corresponding to thickness and shape of the absorbent 30. The core
material 10 is a stacked body of glass wools, in which a glass wool
made by gathering glass fibers with a diameter of 3 to 5 .mu.m is
stacked in two layers, and has a thickness of 120 mm, and the
absorbent securing part 12 is formed in a groove shape with a depth
of 40 mm. When processing the core material into a vacuum
insulation panel, the thickness of the core material is compressed
into 9 mm, and the groove is compressed into a depth corresponding
to the absorbent 30 having a thickness of 3 mm.
FIG. 3 is a view illustrating a process of cutting a portion of the
securing part in the core material 10 with a device 40 for forming
the absorbent securing part 12 in the core material 10 and at the
same time pressing the portion of the securing part to form a
groove. The absorbent securing part forming device 40 is provided
with a cutting knife 42 capable of cutting the portion of the
securing part in the core material where the absorbent is to be
placed and a compression jig 44 which presses the cut portion of
the securing part in the core material. The compression jig 44 is
driven by a compression spring 46. Also, the device 40 is provided
with a guide jig 48 for securing the core material 10, and cutting
and pressing the core material 10 at a correct position. The guide
jig 48 and the cutting knife 42 are connected, and the cutting
knife 42 is projected out of the guide jig 48 to a length
corresponding to a cutting depth of the absorbent securing part.
FIG. 3(a) shows a state that the core material 10 is placed below
the absorbent securing part forming device 40 to prepare formation
of the absorbent securing part. When the core material is prepared,
as shown in FIG. 3(b), the cutting knife 42 connected with the
guide jig 42 cuts the portion of the securing part first while the
absorbent securing part forming device 40 moved down onto the core
material 10. After that, the compression jig 44 presses the cut
portion of the securing part as shown in FIG. 3(b). The compression
jig 44 presses the portion of the securing part by the depth of the
absorbent securing part 12 to be formed. FIG. 3(d) shows the core
material 10 having the absorbent securing part 12 formed through
the process as described above. Unlike the phenomenon that the
periphery is pressed together is shown in a general press process,
it can be seen that the portion of the securing part alone is
clearly cut by previously cutting the portion of the securing part
and then pressing the portion of the securing part. This has a
large influence on enhancement of smoothness of the vacuum
insulation panel.
FIG. 4 is a sectional view illustrating a surface material, in
which a side (A in FIG. 1) of the vacuum insulation panel in
accordance with an embodiment of the present invention is enlarged.
The surface material 20 is a laminate film, which includes, from
the inner side thereof, a thermal bonding layer 22, a gas barrier
layer 24, a first protective layer 26 and a second protective layer
28. The thermal bonding layers 22, or the innermost layers, are
bonded in a state that they face with each other. In the surface
material 20, the thermal bonding layer 22 is made of LLDPE, a
polyethylene resin, with a thickness of about 50 .mu.m, the gas
barrier layer 24 is made of an aluminum foil layer with a thickness
of about 6 .mu.m, the first protective layer 26 is made of a nylon
film with a thickness of about 25 .mu.m, and the second protective
layer 28 is made of a polyethylene terephthalate film (K-PET) with
a thickness of about 12 .mu.m which is coated with polyvinylidene
chloride (PVDC).
Meanwhile, the absorbent 30 employed one in which CaO powder is
sealed with a multilayer film of water resistant paper layer and PP
non-woven layer. In order to prevent that the CaO powder is
gathered into one portion, not only periphery of the packaging
material but also middle portions of the packaging material were
sealed to enhance smoothness of the surface of the vacuum
insulation panel (not shown).
The surface material 20, the core material 10 and the absorbent 30
placed on the securing part 12 of the core material 10 were
disposed in the vacuum insulation panel manufacturing device (not
shown) and the thermal bonding layer 22 were bonded by heating the
surface material 20 to a melting temperature by a heating plate
above and below the surface material 20 and at the same time
performing vacuum exhaustion, thereby manufacturing the vacuum
insulation panel 100. From the result of measurement for a thermal
conductivity of the vacuum insulation panel using thermal
conductivity measuring equipment HC 074-200 (Eco company), it could
be seen that the thermal conductivity of the absorbent securing
part is 0.004662 Kcal/mhr.degree. C. and reduction ratio in the
thermal conductivity at the absorbent securing part is lowered to
1/4 as compared with 0.02024 Kcal/mhr.degree. C., a thermal
conductivity of an absorbent securing part formed by cutting the
core material into a groove shape. That is, in the core material in
which the groove is formed by cutting some of the core material,
difference in thermal conductivity between the core material and
the absorbent securing part is very large and this may cause
deterioration of overall thermal performance of the vacuum
insulation panel. On the contrary, in the core material
manufactured in accordance with the present invention, the
difference in the thermal conductivity is notably reduced to
thereby be able to prevent deterioration of overall thermal
performance of the vacuum insulation panel.
Also, smoothness of the vacuum insulation panel 100 was measured,
and as the result, difference in thickness between the portion
where the absorbent is present and the portion where the absorbent
is not present was 1 mm or less. This improvement in smoothness
notably reduced generation of wrinkle or poor sealing of the
surface material of the vacuum insulation panel and long-term
insulation efficiency was thus enhanced.
While the present invention has been described with respect to the
specific embodiments, it will be apparent to those skilled in the
art that various changes and modifications may be made without
departing from the spirit and scope of the invention as defined in
the following claims.
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